In general, a fuel tank of an automobile is hung under a rear floor panel by belts. Such a fuel tank is filled with a fuel, which sloshes because of acceleration, deceleration, or the like of the vehicle, so that a fuel sloshing sound (splashing sound) is generated. In this respect, various techniques have been proposed conventionally to reduce the fuel sloshing sound.
For example, JP2001-63389A discloses a fuel tank disposition structure in which a recessed portion is formed in a flat floor panel, and a fuel tank is fixed by being pressed onto corner positions of the recessed portion by belts, via pads. It is said that since the rigidity is higher in the corner positions of the recessed portion than in the other flat portions, the technique can reduce the transmission of sound from the fuel tank to the floor panel, and can prevent leakage of the fuel sloshing sound in the fuel tank to the vehicle interior.
In JP2001-63389A, front attachment portions of the belts used to hang the fuel tank are attached to a rear-floor front cross member (a seat cross member) under the floor panel, and it seems according to the drawings that a front surface of the fuel tank does not abut on anything. Setting the front surface of the fuel tank free as described above makes the fuel tank itself not fixed firmly and thus is not preferable from the viewpoint of safety. Meanwhile, suppose a case where the front surface of the fuel tank abuts on the rear-floor front cross member. In such a case, when the front surface of the fuel tank is pressed onto the rear-floor front cross member at the flat surface portion thereof which has a relatively low rigidity, the flat surface portion of the rear-floor front cross member vibrates as a result of the fuel sloshing, and the sound of the fuel sloshing may be transmitted to the vehicle interior.